CN111620223B - Construction method for lifting net rack through secondary stress conversion of support - Google Patents
Construction method for lifting net rack through secondary stress conversion of support Download PDFInfo
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- CN111620223B CN111620223B CN202010446728.2A CN202010446728A CN111620223B CN 111620223 B CN111620223 B CN 111620223B CN 202010446728 A CN202010446728 A CN 202010446728A CN 111620223 B CN111620223 B CN 111620223B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B66—HOISTING; LIFTING; HAULING
- B66C—CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES
- B66C1/00—Load-engaging elements or devices attached to lifting or lowering gear of cranes or adapted for connection therewith for transmitting lifting forces to articles or groups of articles
- B66C1/10—Load-engaging elements or devices attached to lifting or lowering gear of cranes or adapted for connection therewith for transmitting lifting forces to articles or groups of articles by mechanical means
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B66—HOISTING; LIFTING; HAULING
- B66F—HOISTING, LIFTING, HAULING OR PUSHING, NOT OTHERWISE PROVIDED FOR, e.g. DEVICES WHICH APPLY A LIFTING OR PUSHING FORCE DIRECTLY TO THE SURFACE OF A LOAD
- B66F3/00—Devices, e.g. jacks, adapted for uninterrupted lifting of loads
- B66F3/24—Devices, e.g. jacks, adapted for uninterrupted lifting of loads fluid-pressure operated
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04G—SCAFFOLDING; FORMS; SHUTTERING; BUILDING IMPLEMENTS OR AIDS, OR THEIR USE; HANDLING BUILDING MATERIALS ON THE SITE; REPAIRING, BREAKING-UP OR OTHER WORK ON EXISTING BUILDINGS
- E04G21/00—Preparing, conveying, or working-up building materials or building elements in situ; Other devices or measures for constructional work
- E04G21/14—Conveying or assembling building elements
Abstract
The invention belongs to the technical field of hoisting construction of steel mesh frame floor systems in an atrium space, and particularly discloses a construction method for lifting a net frame through secondary stress conversion of a support, the construction method provided by the invention can ensure that the net frame is assembled on a structural surface or a ground position, the assembly of the net frame can be carried out simultaneously with the construction of a surrounding concrete structure, the bottling of the net frame is changed from high-place operation to ground operation, the safety coefficient is improved, the welding quality can be ensured, a large amount of labor and time are saved, and the construction speed is accelerated; after the net rack is assembled on the building and the ground, the positions of partial supports are selected and temporary rods and hanging points are welded according to the calculation of the stress of the net rack units, a secondary stress conversion mechanism is arranged at the top of the corresponding concrete support, the net rack is lifted, statically stopped, rod embedded and supplemented, unloaded and the conversion of the net rack integral stress support is realized through the secondary stress conversion mechanism, and the net rack structure can form an integral stable stress system before and after the conversion of the support through the calculation of working conditions.
Description
Technical Field
The invention belongs to the technical field of hoisting construction of steel mesh frame floors in an atrium space, and particularly relates to a construction method for lifting a mesh frame through secondary stress conversion of a support.
Background
The space grid structure is a net-shaped space rod system structure which is formed by a plurality of rod pieces through nodes according to a certain rule. The grid structure can be divided into a flat grid and a curved grid according to the shape. In general, the flat-plate net frame is simply called net frame; the curved surface net rack is simply called as a latticed shell, the net rack structure is a space rod system structure, has the characteristic of three-dimensional stress, can bear the effect in all directions, is generally a high-order hyperstatic structure, and has the advantages that if one rod is partially failed, only one hyperstatic time is needed, the internal force can be readjusted, the whole structure is generally not failed, and the high safety storage is realized.
Patent application with publication number CN111608397A discloses a net rack installation and construction method, which comprises the following process flows: measurement and positioning of a support point of a net rack → reexamination of raw materials → installation of a lower chord bolt ball and a lower chord of a basic cross net rack → installation of an upper chord bolt ball, an upper chord and a web member of the basic cross net rack → basic cross net rack lifting → connection of the basic cross net rack in place and a support → high-altitude bulk of the rest net rack → repair of paint → acceptance inspection. The construction method of the invention can overcome the problems that the surrounding field of the construction site is narrow, the truck crane is difficult to place and hoist, and the like, and the installation and construction of the space grid structure are realized in the limited space, and the method is efficient, safe and worthy of popularization, along with the more mature space grid structure construction technology, the space grid structure is widely used as the building cover of the building, wherein the installation of the space grid structure is also a key item in the grid structure construction technology, for example, in the building engineering that the steel structure grid is the floor of the top of a four-layer report hall, the concrete structure with the height of 18.5m around is used as a steel structure grid support, only after the concrete construction of the top plate of three layers is finished, the grid splicing operation is started immediately, the realization of the node of the set construction period can be ensured, so the dispatching building engineering can be inserted into the floor splicing work of the grid structure in time after the construction of the first water flowing section of the top plate of three layers is finished, the construction of later stage concrete structure and the synchronous of steel mesh frame structure floor assembly are gone on to utilize concrete structure as the promotion support of steel rack, through promotion and the uninstallation that the secondary atress shifter mechanism of installation in concrete support position realized the rack, finally accomplish the major structure capping in set time limit for a project, it is simple and practical to have confirmed the whole lifting technology of rack support secondary atress conversion, and is economical and effective, safe and reliable saves the time limit for a project, can popularize and apply in similar engineering. Therefore, the technical field provides a construction method for a support secondary stress conversion lifting net rack.
Disclosure of Invention
The invention aims to provide a construction method for a support secondary stress conversion lifting net rack, which aims to solve the problems in the background technology.
In order to realize the purpose, the invention adopts the following technical scheme: a construction method for lifting a net rack by secondary stress conversion of a support comprises the following steps:
s1, the net racks are assembled on the four-layer concrete floor and constructed simultaneously with the four-layer vertical concrete structure after the construction is finished;
s2, performing relevant quality detection and acceptance by the net rack after the floor assembly is completed, and reinforcing maintenance after the construction of the peripheral vertical concrete structure is completed until the strength of the concrete structure reaches 100% of the design strength;
s3, according to the construction scheme, selecting 6 of 18 supports on the east and west sides of the original design as lifting points, and additionally arranging two lifting points on the north side to total 8 lifting points;
s4, 8 secondary stress conversion mechanisms are installed at the top of the selected lifting point, the lifting, the static stopping, the rod piece embedding and unloading of the net rack and the conversion of the integral stress support of the net rack are realized through the secondary stress conversion mechanisms, temporary rod pieces are installed at the corresponding positions of the net rack and are connected with a lifting appliance to form 8 lifting points;
s5, entering a pre-lifting stage when the concrete reaches 100% of the design strength, lifting by 10cm, checking the operation data of equipment and the form change of a net rack, and standing for 12 hours after no error is confirmed;
s6, after standing still for 12 hours, rechecking the operation data of the equipment and the form change of the net rack, and after the rechecking data are confirmed to meet the requirements, increasing the operation data to the designed elevation at one time;
s7, after the steel net frame is lifted, firstly installing net frame members except for 8 hoisting points, and connecting 12 supports which are not used as hoisting points;
s8, synchronously and step-by-step unloading the lifting device after the installation is finished and the acceptance is qualified, and removing 8 lifters and the secondary stress conversion mechanism after the unloading is finished;
and S9, finally, mounting the structural rod piece and the support at the lifting point position in place, applying pre-jacking force to the support and the support ball at the lifting point position to a designed value, and inserting steel plates made of the same material into a gap between the conversion plate at the bottom of the support and the embedded plate of the main body for welding.
Preferably, the step of applying the pre-jacking force to the design value in step S9 includes the steps of:
s2.1, removing the secondary stress conversion mechanism, the temporary lifting point and the temporary rod piece, embedding the rod piece at the lifting point, and calculating the support counter force borne by the support under the design working condition through a structural design stress model to serve as a pre-jacking force applied to the support;
s2.2, applying designed rechecked pre-jacking force to the support ball by using a hydraulic jack and jacking the support, and then tightly cushioning the gap distance between the support plate and the top surface of the finished support by using steel plates with the same thickness and welding and fixing the steel plates to ensure that the stress working condition of the finished net rack is consistent with the design.
Preferably, a proper number of the design support positions of the net rack are selected as net rack hoisting points, the selected hoisting points are used as stress points of the whole net rack when the net rack is lifted, the maximum deflection of the span of the whole net rack is calculated to be not more than L/200, and when the hoisting points are used as supports, the stress ratio of all rods is calculated to be not more than 1.
Preferably, when the net rack support except for the lifting point bears the whole net rack under stress, the maximum deflection of the span of the whole net rack is not more than L/200, and the stress ratio of all rods is not more than 1.
Preferably, in step S4, fusion welding is used to weld the secondary force-receiving conversion mechanism during the installation process, and the steel beam, and the steel beam and the upright web are provided with rib plates at corresponding positions.
Preferably, the secondary force-bearing conversion net rack lifting comprises the following steps:
s6.1, posture detection and adjustment: and (4) detecting the ground clearance of each lifting point by using a measuring instrument, and calculating the relative height difference of each lifting point. The height of each lifting point is adjusted through hydraulic lifting system equipment, so that the structure reaches a horizontal posture;
s6.2, integrally and synchronously lifting: taking the height of each lifting point after adjustment as a new initial position, resetting a displacement sensor, keeping the posture until the lifting point is near a designed elevation in the whole lifting process of the structure, controlling an asynchronous control value to be less than or equal to 20mm, simultaneously adopting manual auxiliary inspection near 8 points of each lifting point in the lifting stage, measuring by using a level gauge to see whether the asynchronous value of each lifting point of the integral net rack is within the control value, if the asynchronous value is exceeded, suspending upward lifting, detecting the lifting point at the position, and continuously lifting after removing the reason;
s6.3, lifting speed: in the integral lifting construction process, factors influencing the lifting speed of the component mainly comprise the length of a hydraulic oil pipe and the configuration number of pump stations, and according to the equipment configuration of the scheme, the integral lifting is about 10 m/h;
s6.4, fine adjustment of the lifting process: in the lifting and descending processes of the structure, because the height fine adjustment is needed for the aerial attitude adjustment, the rod alignment and the like, before the fine adjustment is started, the automatic mode of the computer synchronous control system is switched into the manual mode, the hydraulic lifters of all lifting points in the whole hydraulic lifting system are synchronously micro-moved or a single hydraulic lifter is micro-moved and adjusted according to the needs, the micro-moving, namely the inching adjustment precision can reach millimeter level, and the precision requirement of the installation of the steel structure unit of the net rack can be completely met;
s6.5, synchronous observation: the steel ruler is hung at the position of the steel strand, the net rack lifting height is directly read out from the scale of the steel ruler, and when height difference exists in the lifting process, the net rack lifting height can be immediately and uniformly adjusted.
The invention has the technical effects and advantages that: compared with the prior art:
1. after the net frame is assembled on the building and ground, according to the stress calculation of net frame unit, selecting partial support seat position to weld temporary rod and hanging point, and setting secondary stress conversion mechanism on the top of correspondent concrete support seat, utilizing secondary stress conversion mechanism to implement net frame lifting, static stopping, rod embedding, unloading and net frame integral stress support seat conversion, and utilizing working condition calculation to make the net frame structure form integral stable stress system before and after support seat conversion, after unloading, removing secondary conversion mechanism and temporary lifting rod, welding rear compensation rod and support seat ball at hanging point, utilizing design model to calculate support seat reaction force which the support seat at hanging point position must bear, using hydraulic jack to apply required pre-jacking force to support seat ball, regulating and correcting support seat position stress condition to make the stress working condition of final integral net frame completely identical to design, for hoisting construction of the steel mesh frame floor in the atrium space, the net frame support secondary stress conversion integral hoisting technology is simple and practical, economical, effective, safe and reliable, and the construction period is saved;
2. the construction method provided by the invention can ensure that the net rack is assembled on the structural surface or the ground, the assembly of the net rack can be carried out simultaneously with the construction of the surrounding concrete structure, the bottling of the net rack is changed from high-place operation to ground operation, the safety coefficient is improved, the welding quality can be ensured, a large amount of labor and time are saved, and the construction speed is accelerated; a large-volume full-framing scaffold platform is not required to be erected, so that the field can be effectively utilized, and the measure cost and the safety risk are reduced;
3. the materials used in the method belong to turnover materials, the hydraulic lifter can be reused after being detached, only manual assembly and lifting operation of the lifter are needed during each use, the cost is low, and the method is economical and applicable; the construction method can carry out the construction of the surrounding concrete structure support and the installation of the lifting device while the net racks are assembled, can effectively improve the working efficiency and shorten the construction period; when the construction method is used for construction, the net racks can be integrally assembled on the ground, so that high-altitude operation is avoided, the working efficiency can be improved, the construction period is shortened, the quality is ensured, and the construction safety risk is effectively reduced; the machine used in the method belongs to the field of tool operation, is simple and easy to learn, is convenient to operate and has good stability.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:
fig. 1 is a schematic view of the arrangement of net rack lifting points of the present invention;
FIG. 2 is a schematic view of the down winding structure of the present invention;
FIG. 3 is a schematic view of a fulcrum reaction structure in the present invention;
FIG. 4 is a stress ratio structure diagram of the rod member according to the present invention;
FIG. 5 is a schematic view of an arrangement of rod replacement regions according to the present invention;
FIG. 6 is a schematic view of a winding structure after the rod member is replaced;
FIG. 7 is a schematic view of a counter force structure of a point after a rod member is replaced;
FIG. 8 is a structural diagram of stress ratio of the rod after replacement according to the present invention;
FIG. 9 is a schematic diagram of a planar structure of a secondary force conversion mechanism arrangement according to the present invention;
FIG. 10 is a schematic structural diagram of a secondary force conversion mechanism according to the present invention;
FIG. 11 is a schematic diagram illustrating the structural effect of the secondary force conversion mechanism of the present invention;
FIG. 12 is a parameter table of the rod member of the secondary force conversion mechanism of the present invention;
fig. 13 is a schematic view of the reaction force of the abutment in the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The specific embodiments described herein are merely illustrative of the invention and do not delimit the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1 to 13, the present invention provides a construction method for a support secondary stress conversion hoisting net rack, comprising the following steps:
s1, the net racks are assembled on the four-layer concrete floor and constructed simultaneously with the four-layer vertical concrete structure after the construction is finished;
s2, performing relevant quality detection and acceptance by the net rack assembled on the floor, and reinforcing maintenance after the construction of the vertical concrete structures on the periphery is completed until the strength of the concrete structure reaches 100% of the design strength;
s3, according to the construction scheme, selecting 6 lifting points from 18 supports on two sides of an original design object, and additionally arranging two lifting points on the north side to obtain 8 lifting points;
s4, 8 secondary stress conversion mechanisms are installed at the top of the selected lifting point, the lifting, the static stopping, the rod piece embedding and unloading of the net rack and the conversion of the integral stress support of the net rack are realized through the secondary stress conversion mechanisms, temporary rod pieces are installed at the corresponding positions of the net rack and are connected with a lifting appliance to form 8 lifting points;
s5, entering a pre-lifting stage after the concrete reaches 100% of the design strength, lifting by 10cm when lifting, checking the operation data of equipment and the form change of a net rack, and standing for 12 hours after the situation is confirmed to be correct;
s6, after standing still for 12 hours, rechecking the operation data of the equipment and the form change of the net rack, and after the rechecking data are confirmed to meet the requirements, increasing the operation data to the designed elevation at one time;
s7, after the steel net frame is lifted, firstly installing net frame members except for 8 hoisting points, and connecting 12 supports which are not used as hoisting points;
s8, synchronously and gradually unloading the lifting device after the mounting is finished and the mounting is qualified, and removing 8 lifters and the secondary stress conversion mechanism after the unloading is finished;
and S9, finally, mounting the structural rod piece and the support at the lifting point position in place, applying pre-jacking force to the support and the support ball at the lifting point position to a designed value, and inserting steel plates made of the same material into a gap between the conversion plate at the bottom of the support and the embedded plate of the main body for welding.
Specifically, the step of applying the pre-jacking force to the design value in step S9 includes the steps of:
s2.1, removing the secondary stress conversion mechanism, the temporary lifting point and the temporary rod piece, embedding the rod piece at the lifting point, and calculating the support counter force borne by the support under the design working condition through a structural design stress model to serve as a pre-jacking force applied to the support;
s2.2, applying designed rechecked pre-jacking force to the support ball by using a hydraulic jack and jacking the support, and then tightly cushioning the gap distance between the support plate and the top surface of the finished support by using steel plates with the same thickness and welding and fixing the steel plates to ensure that the stress working condition of the finished net rack is consistent with the design.
Specifically, a proper number of the hoisting points are selected from the positions of the net rack design support as net rack hoisting points, the selected hoisting points are used as stress points of the whole net rack when the net rack is lifted, the maximum deflection of the span of the whole net rack is calculated to be not more than L/200, and when the hoisting points are used as the support, the stress ratio of all the rods is calculated to be not more than 1.
Specifically, when the net rack support except for the lifting point bears the whole net rack under stress, the maximum deflection of the span of the whole net rack is not more than L/200, and the stress ratio of all the rods is not more than 1.
Specifically, in step S4, fusion welding is used to weld the secondary force-receiving conversion mechanism during the installation process, and the steel beam, and the steel beam and the upright web are provided with rib plates at corresponding positions.
Specifically, the secondary stress conversion net rack lifting comprises the following steps:
s6.1, posture detection and adjustment: and (4) detecting the ground clearance of each lifting point by using a measuring instrument, and calculating the relative height difference of each lifting point. The height of each lifting point is adjusted through hydraulic lifting system equipment, so that the structure reaches a horizontal posture;
s6.2, integrally and synchronously lifting: the height of each lifting point after adjustment is taken as a new initial position, a displacement sensor is reset, in the whole lifting process of the structure, the posture is kept until the lifting point is lifted to the vicinity of the designed elevation, the asynchronous control value is controlled to be less than or equal to 20mm, manual auxiliary inspection is adopted in the vicinity of 8 points of each lifting point in total in the lifting stage, a gradienter is adopted to measure whether the asynchronous value of each lifting point of the whole net rack lifting is within the control value or not, if the asynchronous value is exceeded, upward lifting is suspended, the lifting point at the position is detected, and the lifting can be continuously lifted after the reason is eliminated;
s6.3, lifting speed: in the integral lifting construction process, factors influencing the lifting speed of the component mainly comprise the length of a hydraulic oil pipe and the configuration number of pump stations, and according to the equipment configuration of the scheme, the integral lifting is about 10 m/h;
s6.4, fine adjustment of the lifting process: in the lifting and descending processes of the structure, because the height fine adjustment is needed for the aerial attitude adjustment, the rod alignment and the like, before the fine adjustment is started, the automatic mode of the computer synchronous control system is switched into the manual mode, the hydraulic lifters of all lifting points in the whole hydraulic lifting system are synchronously micro-moved or a single hydraulic lifter is micro-moved and adjusted according to the needs, the micro-moving, namely the inching adjustment precision can reach millimeter level, and the precision requirement of the installation of the steel structure unit of the net rack can be completely met;
s6.5, synchronous observation: the steel ruler is hung at the position of the steel strand, the net rack lifting height is directly read out from the scale of the steel ruler, and when height difference exists in the lifting process, the net rack lifting height can be immediately and uniformly adjusted.
The process principle and the construction flow of the invention are as follows: the key technology in the hydraulic integral synchronous lifting of the spherical welding net rack is that the lifting point selection process, the arrangement of a secondary conversion mechanism, the stress adjustment of individual supports after the net rack is lifted in place and the unloading stress conversion is completed, the lifting points temporarily welded on the net rack and the lifting supports on the upper concrete structure surface are calculated through working conditions, the stress check calculation of individual rods does not pass under the non-design working condition, the individual rods can be replaced and enhanced, the net rack is ensured to be an integral stable stress system in the lifting process and before and after the support conversion, the secondary conversion mechanism is arranged on the selected concrete lifting support, the net rack is lifted, statically stopped, rod embedded and supplemented, unloaded and the integral stress support conversion of the net rack is realized through the conversion mechanism, after the support conversion is completed, the temporary lifting rods are removed, the rest rod links are embedded and supplemented, and the support is stressed under the original design working condition through calculation, and (3) using a hydraulic jack to jack the support ball, applying a designed rechecked pre-jacking force to the support ball, and then tightly cushioning and welding and fixing the gap distance between the support plate and the top surface of the finished support by adopting steel plates with the same thickness, so that the stress working condition of the unloaded net rack is completely consistent with the design.
In the invention: according to the structural characteristics of the roof grid structure and the stress calculation simulation analysis of the grid units, lifting hoisting points are arranged at the two ends of the grid, 8 hoisting points are arranged in total for integral lifting, and the arrangement of the hoisting points is shown in figure 1; the SAP2000 is adopted to simulate the integral lifting working condition of the net rack, and the main stress conditions of the structure are shown in figures 2, 3 and 4; under the lifting working condition, the maximum deflection of the span of the net rack is about 40mm (the L/200 meeting the standard requirement is 264mm), the reaction force value of a lifting point is about 549KN at most, the stress ratio of 68 structural rod pieces does not meet the requirement, the structural rod pieces need to be replaced, and the arrangement of a rod piece replacement region is shown in fig. 5; by replacing 68 rod pieces, under the lifting working condition, the maximum mid-span of the net rack is deflected downwards by about 39mm (the L/200 meeting the specification requirement is 264mm), as shown in fig. 6; the lifting point reaction force value is about 557KN (as shown in figure 7) at most, the stress ratio of the rod piece is below 0.8 (as shown in figure 8), and the lifting requirement is met; the total weight of the rod piece before replacement is 3163kN, the total weight of the rod piece after replacement is 3180kN, 17kN is added, and the cross section which is originally designed by adopting the calculation result of the 3D3S software on the structure and the stress of the welding ball under the lifting working condition can meet the stress under the lifting working condition; according to the structural characteristics of the frame columns and the net racks and the stress calculation simulation analysis of the net rack units, 8 conversion mechanisms are arranged, the stress checking calculation of the structure per se meets the design requirements, and the on-site lifting conditions are met as shown in fig. 9, fig. 10 and fig. 11; the parameters of the rod elements of the secondary force conversion mechanism are shown in fig. 12, and the support reaction force to be born by the support originally serving as the lifting point is shown in fig. 13 according to the net rack calculation model.
The quality control in the invention is as follows:
1. quality control in a lifting process
1.1, controlling the axis of the net rack: in order to ensure the accuracy of the installation of the support, the axis of the integral hoisting of the net rack must be strictly controlled.
(1) When the net rack is assembled on the ground, the plane geometric dimension of the side support is strictly controlled. Considering that the post construction is finished when the net rack is assembled, the post center line is taken as the center line of the side support when the net rack is assembled, so as to eliminate the error accumulation of foundation construction, paying off, post installation and foundation axis.
(2) After the net rack is assembled, the deviation value of the side support of the net rack and the central line of the column corresponding to the side support of the net rack is actually measured, and an error map of the assembling of the net rack is drawn. The column top displacement graph and the net rack assembly error graph are put together, comparative analysis is carried out, the size and the direction of the error are comprehensively considered, the position where the net rack is actually installed is found, and a net rack installation superposition graph is drawn. The rack is mounted in place according to the dimensions noted on the superimposed graph.
2. Control of net rack deflection in lifting process
2.1, a detection method: and checking retest records and test reports.
2.2, the bending values of the net rack structure after the self weight and the roof engineering are finished are as follows:
the safety measures in the invention are as follows:
1. checking before lifting: before lifting, the lifting device will be checked as follows:
1.1, checking whether a lifting device meets design requirements or not, and checking whether the specification and model of an oil pipe meet the requirements or not; after the net rack is lifted, the guy cables at the lifting points are fastened, the verticality and the base condition of the lifting device are checked, and the quality of the lifting device is guaranteed.
And 1.2, checking whether the temporary lifting point of the net rack is intact or not, and ensuring smooth running of the pulley in construction due to cracks, corrosion and the like.
And 1.3, checking whether the material and specification of the steel strand meet the requirements, whether the length meets the construction requirements, and whether a fracture point and a corrosion point exist.
1.4, the rope clip, the rope buckle and the guy rope need to be checked whether the specification meets the requirements or not, whether the specification is damaged or not is judged, and the safety of construction and use is ensured.
And 1.5, checking whether the ground anchor is firmly embedded or not and whether the joint part of the ground anchor and the guy rope is firm or not.
And 1.6, carrying out comprehensive inspection on other equipment to ensure the normal operation of each piece of construction equipment.
2. In-lift inspection
In the lifting process, the following conditions are monitored at any time, if abnormal conditions exist, the lifting is immediately stopped, each pump source control valve is automatically closed, and the hydraulic lock of the lifter is automatically locked; and immediately analyzing the cause of the problem and rapidly solving the problem. The problems which cannot be solved need to be reported in time, and construction can be continued after the problems are solved.
2.1, the position of the temporary hoisting point, deformation, verticality and stability of steel strand connection.
2.2, whether the running room of the hydraulic lifter is normal or not, whether obstacles exist on the motion trail or not, and if the obstacles exist, timely cleaning is needed.
2.3, a tension meter is arranged on the hydraulic lifter, and the change of the tension of the running rope in the lifting process is monitored at any time.
2.4, the safety of rope clip, rope fastening, whether check rope clip, rope fastening chucking, straining, arrange the special messenger and patrol the inspection, firmly stop irrelevant personnel to the contact of rope clip, rope fastening.
And 2.5, determining the stress condition of the steel strand according to the stress condition of the steel strand and the clamping condition of a rope clamp fixed at one end of the ground anchor through a tension meter and observation.
And 2.6, observing whether the ground anchor is loosened or not, and dispatching a person for monitoring for 24 hours.
The environmental protection measures in the invention are as follows:
1. the waste engine oil for construction and welding slag and waste material produced by electric welding are stored, recovered and transported in a centralized way.
2. The construction site is required to be clean after the material is finished.
3. The equipment and the material are placed safely and reasonably, and the construction site does not have illegal operation.
Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments or portions thereof without departing from the spirit and scope of the invention.
Claims (6)
1. A construction method for lifting a net rack through secondary stress conversion of a support is characterized by comprising the following steps:
s1, the net racks are assembled on the four-layer concrete floor and constructed simultaneously with the four-layer vertical concrete structure after the construction is finished;
s2, performing relevant quality detection and acceptance by the net rack after the floor assembly is completed, and reinforcing maintenance after the construction of the peripheral vertical concrete structure is completed until the strength of the concrete structure reaches 100% of the design strength;
s3, according to the construction scheme, selecting 6 lifting points from 18 supports on two sides of an original design object, and additionally arranging two lifting points on the north side to obtain 8 lifting points;
s4, 8 secondary stress conversion mechanisms are installed at the top of the selected lifting point, the lifting, the static stopping, the rod piece embedding and unloading of the net rack and the conversion of the integral stress support of the net rack are realized through the secondary stress conversion mechanisms, temporary rod pieces are installed at the corresponding positions of the net rack and are connected with a lifting appliance to form 8 lifting points;
s5, entering a pre-lifting stage when the concrete reaches 100% of the design strength, lifting by 10cm, checking the operation data of equipment and the form change of a net rack, and standing for 12 hours after no error is confirmed;
s6, after standing still for 12 hours, rechecking the operation data of the equipment and the form change of the net rack, and after the rechecking data are confirmed to meet the requirements, increasing the operation data to the designed elevation at one time;
s7, after the steel net frame is lifted, firstly installing net frame members except for 8 hoisting points, and connecting 12 supports which are not used as hoisting points;
s8, synchronously and gradually unloading the lifting device after the mounting is finished and the mounting is qualified, and removing 8 lifters and the secondary stress conversion mechanism after the unloading is finished;
and S9, finally, mounting the structural rod piece and the support at the lifting point position in place, applying pre-jacking force to the support and the support ball at the lifting point position to a designed value, and inserting steel plates made of the same material into a gap between the conversion plate at the bottom of the support and the embedded plate of the main body for welding.
2. The construction method of the support secondary stress conversion hoisting net rack according to claim 1, characterized in that: applying the pre-jacking force to the design value in step S9 includes the steps of:
s2.1, removing the secondary stress conversion mechanism, the temporary lifting point and the temporary rod piece, embedding the rod piece at the lifting point, and calculating the support counter force borne by the support under the design working condition through a structural design stress model to serve as a pre-jacking force applied to the support;
s2.2, applying designed rechecked pre-jacking force to the support ball by using a hydraulic jack and jacking the support, and then tightly cushioning the gap distance between the support plate and the top surface of the finished support by using steel plates with the same thickness and welding and fixing the steel plates to ensure that the stress working condition of the finished net rack is consistent with the design.
3. The construction method of the support secondary stress conversion hoisting net rack according to claim 1, characterized in that: selecting proper quantity as net rack hoisting points from the net rack design support positions, taking the selected hoisting points as stress points of the whole net rack when the net rack is lifted, calculating that the maximum deflection of the span of the whole net rack is not more than L/200, and calculating that the stress ratio of all the rods is not more than 1 when the hoisting points are used as supports.
4. The construction method of the support secondary stress conversion hoisting net rack according to claim 1, characterized in that: when the net rack support except for the lifting point bears the net rack as a whole, the maximum deflection of the span of the whole net rack is not more than L/200, and the stress ratio of all the rods is not more than 1.
5. The construction method of the support secondary stress conversion hoisting net rack according to claim 1, characterized in that: and in the step S4, adopting fusion penetration welding to weld in the installation process of the secondary stress conversion mechanism, wherein rib plates are arranged at the corresponding positions of the steel beam and the web plate of the upright post.
6. The construction method of the support secondary stress conversion hoisting net rack according to claim 1, characterized in that: the secondary stress conversion net rack lifting comprises the following steps:
s6.1, posture detection and adjustment: detecting the ground clearance of each lifting point by using a measuring instrument, and calculating the relative height difference of each lifting point; the height of each lifting point is adjusted through hydraulic lifting system equipment, so that the structure reaches a horizontal posture;
s6.2, integrally and synchronously lifting: the height of each lifting point after adjustment is taken as a new initial position, a displacement sensor is reset, in the whole lifting process of the structure, the posture is kept until the lifting point is lifted to the vicinity of the designed elevation, the asynchronous control value is controlled to be less than or equal to 20mm, manual auxiliary inspection is adopted in the vicinity of 8 points of each lifting point in total in the lifting stage, a gradienter is adopted to measure whether the asynchronous value of each lifting point of the whole net rack lifting is within the control value or not, if the asynchronous value is exceeded, upward lifting is suspended, the lifting point at the position is detected, and the lifting can be continuously lifted after the reason is eliminated;
s6.3, lifting speed: in the integral lifting construction process, factors influencing the lifting speed of the component mainly comprise the length of a hydraulic oil pipe and the configuration number of pump stations, and according to the equipment configuration of the scheme, the integral lifting speed is about 10 m/h;
s6.4, fine adjustment of the lifting process: in the lifting and descending processes of the structure, because the height fine adjustment is needed for the aerial attitude adjustment, the rod alignment and the like, before the fine adjustment is started, the automatic mode of the computer synchronous control system is switched into the manual mode, the hydraulic lifters of all lifting points in the whole hydraulic lifting system are synchronously micro-moved or a single hydraulic lifter is micro-moved and adjusted according to the needs, the micro-moving, namely the inching adjustment precision can reach millimeter level, and the precision requirement of the installation of the steel structure unit of the net rack can be completely met;
s6.5, synchronous observation: the steel ruler is hung at the position of the steel strand, the net rack lifting height is directly read out from the scale of the steel ruler, and when height difference exists in the lifting process, the net rack lifting height can be immediately and uniformly adjusted.
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